This invention relates to an automatic steering device for a marine vessel and more particularly to an automatic steering device wherein the course can easily be maintained and abrupt alterations in the steering component of the vessel are avoided.
FIG. 1 illustrates a conventional automatic steering device for a watercraft which watercraft is identified generally by the reference numeral 11 and includes a steering device such as a rudder 12. The rudder 12 is operated by a suitable driver circuit 13 which, in turn, is controlled by means of a control system that includes a part of a controller, indicated schematically at 14, a course fixing device 15 by which the operator set the desired course. The vessel 11 is provided with a bow azimuth detector 16 such as a gyro compass or the like and which outputs a signal to a comparator 17 so as to compare the course fixed by the course fixing device 15 with the actual course determined by the azimuth detector 16. This difference signal is outputted to a processor 18 which is controlled by an input 19 so as to provide an output control to a controller 21 which, through a switch 22, controls the steering driver 13 so as to position the rudder 12 and maintain the vessel 11 on the desired course.
FIG. 2 shows the results of the operation of a conventional automatic steering device. As may be seen, the vessel, when travelling from the point O to the point A deviates along the course P, there is a situation when the course deviation reaches a fairly substantial amount as indicated at the dimension x. When this occurs, the steering device 13 will operate the rudder 12 and effect a substantial change in the steering which can cause an abrupt course deviation that can be unsettling to the passengers. This type of situation is very common with this type of device and, obviously, not particularly desirable.
It is, therefore, a principal object of this invention to provide an improved automatic steering device wherein substantial course deviations are not permitted and wherein substantial course modifications are not required.
It is a further object of this invention to provide an improved steering arrangement for a watercraft wherein the steering control of the watercraft is automatically maintained and is preset by means of a device which is simple and insures against large course deviations.